<p>Methane (CH₄), the primary constituent of natural gas (<i>ca</i>. 95%, volume fraction), serves as a pivotal clean energy resource. Effective CH₄ purification remains a formidable challenge due to its co-existence with CO₂ and higher hydrocarbons (C₂H₆/C₃H₈). Metal-organic frameworks (MOFs) have emerged as energyefficient alternatives to cryogenic distillation by leveraging their tunable host-guest chemistry. Herein, we present a methyl-functionalized pillar-layered MOF, Ni-MPC-BPy, synthesized via hydrothermal assembly of the methyl-decorated pyrazole carboxylate ligand and bipyridine with Ni²⁺. This material shows high adsorption capacities of CO₂/C₃H₈/C₂H₆ and preferential capture of CO₂ and C₂₊ hydrocarbons over CH₄ [ideal adsorbed solution theory (IAST) selectivity: CO₂/CH₄=6.2; C₃H₈/CH₄=288.6; C₂H₆/CH₄=20], validated by dynamic breakthrough experiments achieving enrichment capacities of 29.6 and 79.9 mL/g of CH₄ with 99.9% purity for mixtures of CO₂/CH₄ and C₃H₈/C₂H₆/CH₄, respectively. Grand Canonical Monte Carlo simulations unveil that the engineered methyl motifs strengthen C₂H₆/C₃H₈ binding through cooperative C-H…O/C interactions and van der Waals contacts. This work establishes ligand functionalization as a potent strategy to tailor MOF pore chemistry for modulating the hostguest interactions, advancing the design of separation materials for sustainable natural gas valorization toward carbon-neutral energy systems.</p>